Fuel bricks from lignin and coal fines

Nicole Brown

Leidy Peña

Curtis Frantz

Brett Diehl

Gareth Mitchell

Fred Cannon

Society of Wood Science

and Technology

June 2015

[CNN]

Application: Metal casting

A cupola is a vertical furnace used to melt cast iron; coke is

the fuel source

Coke

When many bituminous coals are heated, they

soften, swell and re-solidify into a porous solid

http://i00.i.aliimg.com/img/pb/907/055/778/778055907_680.jpg

Can lignin-bound anthracite fines

become coke substitutes?

Coke properties

The cupola furnace

Lignin-bound anthracite

fines

Motivation

Coking is an energy intensive and highly polluting process, but

is necessary to achieve desired morphology of coke

Lignin, anthracite fines and collagen are all by-products of

existing industries, should be inexpensive

There is no other current use for anthracite fines, vast stocks

exist

Heterogeneity of the lignin is well-tolerated

Coking is not needed (saves 20% of material, plus reduced

emissions)

Anthracite doesn’t “coke” (expand and

fuse), so it isn’t cokable

High fixed carbon content

Low volatile matter

Clean combustion

High heating values

Low sulfur and nitrogen

Hard and brittle

[Pitt.edu]

Anthracite processing regions

Anthracite processing regions

Anthracite fines were mixed with lignin, collagen,

and silicon, then pressed into a briquette

1 Kg briquettes: 89% anthracite fines, ~5%

lignin, 6% other additives

Coke

Pilot test: 8 Tons of bricks were made,

tested at 2 foundries

Nieto-Delgado, C. et al. 2014. Bindered anthracite briquettes as fuel alternative to metallurgical coke:

Full scale performance in cupola furnaces. Fuel 121, 39-47.

Anthracite fines are hold together by

collagen, lignin and SiC

Collagen is binding agent at room temperature

Lignin at medium temperature regime

SiC at high temperature regime

Lignin thermochemical evolution has been

studied (13C SS NMR), also Raman (not shown)

Briquette strength has been studied

0

1000

2000

3000

4000

5000

6000

7000

0 2 4 6 8

UC

str

engt

h (

kPa)

Lignin amount (%)

Softwood

Eucalyptus Hardwood

Oak Hardwood

No Lignin

Figure from: Lumadue, M. R., Cannon, F. S., & Brown, N. R. (2012). Lignin as both fuel

and fusing binder in briquetted anthracite fines for foundry coke substitute. Fuel, 97, 869-

875. Elsevier Ltd.

Today: Morphology

Lab scale briquettes were pyrolyzed to simulate

heat exposure in the cupola

2.54 cm

5.08 cm

N2

800°C1400°C or

1600°C

Reflected light analysis-specimen preparation

Reflected light image of the polished surface of a briquette pyrolyzed at 800°C for 2 h

Reflected light images of polished surfaces

1400°C 1400°C

1600°C 1600°C

SEM of lignin-bound anthracite fines after 2h

pyrolysis

1400°C 1600°C

SEM suggests a difference in the crystal structure from 1400 to 1600°C

1400°C 1600°C

XRD analysis of a decarbonized sample that was treated at 1600°C for 2h

15 25 35 45 55 65

800°C

15 25 35 45 55 65

1400°C▪

•

•

▪

15 25 35 45 55 65

1600°C

▪

• β-SiC

▪ Si•

•

•

• •

▪

▪

▪

▪

▪

▪

5 15 25 35 45 55 65

Anthracite ash

Semi-quantitative analysis from XRD data of

decarbonized briquettes

Mineral/Phase Raw 800°C 1400°C 1600°C

3C-SiC -- -- 11.1 62.2

2H-SiC -- -- -- 5.5

4H-SiC -- -- -- 14.6

Si 35.9 23.9 16.5 1

TEM of a sample treated at 1400°C for 2h, the

sample was decarbonized for analysis

C O

TEM of a sample treated at 1600°C for 2h, the

sample was decarbonized for analysis

C O Si

In conclusion, lignin, collagen and silicon form a

binder phase that holds anthracite fine grains

Reflectance analysis of pyrolyzed briquettes

revealed the existence of a binder phase

Volatilization of lignin and collagen provides

strength, leaves round pores of thin walls

formed by pressurized and confined gases

within the matrix

Silicon compounds behave as filler phase

occupying the interstitial spaces of anthracite

grains, at high temperatures form bridges,

crystals, nanowires

Acknowledgements

This research is supported by USDA, NIFA grant 2011-67009-

20049

Other components added to the cupola

furnace

Si, SiC, FeC, FeSi, FeMn

Elemental analysis of pyrolyzed

lignin

C H N S O

Lignin 1200°C 94.68 0.11 0.17 1.45 3.59

Lignin 1400°C 97.32 0.06 0.11 0.89 1.63